I've heard that particular spam-defense before, and it's clever. The problem is that you are stuck with the copyright holder's definition of "spam", which has a high possiblity for abuse. It's potentially a new ICANN/VeriSign in the making. Sure, you could get everyone to try using a new haiku with a different copyright holder, but once the idea is entrenched, it'll be about as easy to switch everyone to that haiku as it is to switch everyone to alternative DNS root servers.

(Meta-thought: a lot of proposed or even implemented spam solutions are as bad or worse than the problem. This is one of them.)